Think of a situation when one or more albums are represented by a single image. Clicking a album will not result in a navigation to the album's own URL. They open in the lightbox right away. The complete album is only accessible in the lightbox this way.
By default, when the representative (cover) image is the first photo in each album, it's no problem.
We could let the user pick the cover from:
- an arbitrary photo, not from the album
- a photo of the album
If the photo is not from the album, we assume it's a custom cover (like a mosaic) and it's not meant to be shown in the lightbox anyway. The lightbox will start with the first photo of the album as normal. I guess it's ok?
If the photo is part of the album:
- Reject the custom cover photo and just use the first image? Looks easy. Then why even allow picking the cover photo from the album? In another gallery mode it's still useful: when the albums open on separate pages with thumbnails of every photo.
- Make the lightbox set open at the cover photo? This could make the user arrive in the middle of the photo set, e.g. 46/80 photos, probably missing half the story.
- Move the cover photo to the beginning? This would result in a "broken order" because the photo would not be where it normally belongs.
- Copy the the cover photo to the beginning, but also keep it where it belongs? What if the cover photo is at 3/80 photos? The visitor would see the repeat soon.
- Anything else? How to best handle this?